Process for the production of laterally non-reversed positive copies by heat development



Patented Nov. 7, 1961 PROCESS FOR THE PRODUCTEGN F LATERALLY NON-REVERSED POSITHVE CGPEES BY HEAT DEVELUPMENT Hildegard Haydn and Anita von Ktinig, Leverkusen,

Germany, assignors to AGFA Alitiengesellschaft, Leverkusen, Germany, a corporation of Germany No Drawing. Filed Jan. 31, 1956, Ser. No. 562,613 Claims priority, application Germany Feb. 11, 1955 Claims. (Cl. 96-29) The present invention relates to the production of laterally non-reversed positive copies by means of the known step of heat development of a silver halide layer, the developing operation being coupled with a transfer process. In this process, the developer substance which is contained in a photographic silver halide emulsion layer and which has not been used up at the unexposed areas of said layer is transferred to a second layer which is in contact with the first layer and which contains one or more substances sensitive or insensitive to light which yield colored compounds with the said developer substance. Aromatic diazo and nitroso compounds have been proposed as examples of reaction components in the positive layer.

In a further development of this process, it has now been found that for forming azo dyestuffs in the transfer layer, the speed at which the dyestuffs are formed and also the depth of color can be improved by adding heavy metal salts, if desired together with oxidizing agents, to the transfer layer.

Examples of heavy metal salts which can be used for the purpose of the invention are bichrornates, molybdates, tungstates, vanadates, uranates, titanates, niobates, and tantalates. Preferably salts are used wherein the anions contain a heavy metal atom and the cations are either alkaline metals or NH As oxidizing agents there may be used all compounds which may be handled in the heat without hazard and which may be water-soluble or waterinsoluble, for instance perborates, arsenates, persulfates, chlorates, bromates, iodates and nitrates, preferably the alkali metal and kaline earth metal salts of said compounds.

The diazo compounds may be simple or stabilized compounds, for instance:

Quinone diazides, such as diazo-Z-naphthol-4-sulphonic acid, diazo-Z-naphthol-6-bromo-4-sulphonic acid, diazosulphonates, such as 3-diazo-4-methoxy-6-benzoylaminotoluyl-sulfonate, 4-diazo-4'-methoxy-diphenylamino-sulfonate, 3 diazo 4 methoxy 6 benzoylaminotoluyl-finaphthalinsulfonate, diazoamino compounds, such as diazoamino compounds of diazotized anthranilic acid and ptoluidine, or diazoamine compounds of the sodium salt of diazotized 4-sulfoanthranilic acid and p-toluidine, furthermore, double salts of diazo compounds, such as double salts with the halides and sulfates of zinc, aluminum or magnesium as well as borontrifluoride and arylsulfonates, e.g. p-diazo-diethylaniline-zinc chloride-double salt; 4- diazo-4'-methoxydiphenylaminezinc chloride-double salt; 4,4'-tetraazo 3,3'-di-methoxydiphenyl-borontetrafiuoride.

The diazo compounds are added to the solution used for the preparation of the transfer layer preferably in concentrations of 0.52%. The heavy metal salts are preferably applied in quantities of 540% as calculated on the Weight of diazo compounds used. The oxidizing agent is preferably applied in a quantity of double to four times the weight of the heavy metal salt.

The reactivity is increased by adding acids or acid salts to the transfer layer. The pH value of the solution used for the preparation of said layers shall be the lower, the higher the stabilization degree of the diazo compound. It is preferably adjusted between 2 and 7. As acids which are especially suitable for this purpose there may be mentioned sulfuric and phosphoric acid. The acid is added in a quantity of about 20-100 ml. of H 50, (10%) per liter of transfer solution if for instance quinone diazides are used. If diazoamine compounds are used the solutions for the preparation of the transfer layer are gen erally kept neutral or weakly acid by addition of citric acid or acetic acid, or similar weak acids.

For the preparation of the negative layer about 520 g., preferably 8-13 g. of developer substance are added to 1 liter of silver halide emulsion. The emulsion is adjusted to a pH of about 4-7, preferably 5.6-6.3 by addition of alkali for instance sodium acetate, or acids, for instance citric acid. The choice of the pH-value depends on the developer substance used and is lower with diamino or amino hydroxy compounds than with its dihydroxy compounds.

Any silver halide emulsion can be used as negative layer, such as for example silver chloride, silver bromide and silver iodide emulsions, if desired suitably mixed with one another, of high or low sensitivity, of soft, normal or steep gradation and also with normal, high or low silver content.

Suitable developer substances are the well known aromatic amino or hydroxy compounds or aminohydroxy compounds, with inclusion of amino or hydroxy compounds and aminohydroxy compounds of diphenylamine and diphenyl, e.g. 3-amino-4-oxydiphenyl, 2-amino-3-oxydiphenyl, 3-4-dioxydiphenyl, 3-4-dioxydiphenylamine, 2- amino-3-oxy-diphenylamine, 2amino 5 oxy-diphenylamine, 2-3-diaminodiphenylamine. It is also possible to use aminoand hydroxy compounds or aminohydroxy compounds of naphthalene, which are substituted at the amino group by aliphatic, araliphatic or aromatic radicals or by sulphonic acid or SO R radicals, in which R stands for hydroxyl, alkyl, aryl or aralkyl. These compounds can be substituted in the aromatic nucleus, for example, with halogen, nitro or alkyl radicals.

Compounds of this type are, for example:

IITHSOzCHs IIVHSOaH 11 l nsozgons r ruom -0H o1-r The developing substances used must of course be able to couple with the diazo-compounds contained in the transfer layer to yield azo dyestuffs.

All film-forming colloids in general use for photographic purposes can be used as binding agents for the layers, for example, -gelatine, hydrophylic cellulose derivatives, such as partially hydrolysed acetyl cellulose, polyvinyl alcohol, polyvinyl pyrrolidone or mixtures of these substances. Depth of color and shade of the image tone can be influenced by small additions of heavy metal salts, such as copper sulfate, zinc sulfate, ferric nitrate, chromium alum, cerium nitrate, uranium nitrate, Reinecke salt ((Cr(NH (SCN) ).NH .H O), and others.

For certain purposes, it can be advantageous for the transfer paper to be coated on both sides, so that the positive paper can be arranged between two negative papers in the heat development, whereby a double-sided copy is obtained in a single operation.

For carrying out the process the silver halide layer is exposed to an object to be reproduced and thereafter brought in contact with the transfer layer. The combined layers are then heated for about 60 seconds to a temperature of about 50-180" C., preferably 80150 C., whereby the transfer layer may be heated to a somewhat lower temperature, such as 90-110 C., than the silver halide layer. Hot presses, high glaze presses which can be heated electrically, drying drums and the like are suitable for carryingout the process. After separating the two layers a laterally correct color reproduction of the original to be reproduced is obtained.

EXAMPLE 1 Negative material 30 g. of 1-amino-2-naphthol, 30 g. of potassium-metabisulphite and 45 g. of acetic acid, are added to one liter of silver halide emulsion. Stabilizers and other conventional additives can be used. The emulsion is cast on a paper support and dried.

Positive layer 8 g. of diazotized 1-amino-2-naphthol-4-sulphonic acid, 0.4 g. of ammonium molybdate and 1.0 g. of sodium perborate are dissolved in 500 cc. of water. 80 cc. of sulphuric acid, 500 cc. of 10% polyvinyl alcohol and 100 cc. of glycerine are then added to this solution. It is cast onto any suitable support such as paper and dried.

Processing After exposure of the negative the same is contacted with the transfer paper and heated by means of a hot press to 90150 C., preferably 110135 C., for 5-20 seconds. After separating the two layers, the positive is obtained with a bluish violet color.

EXAMPLE 2 Negative material As in Example 1.

Positive material 10 g. of diazotized 1-amino-2-naphthol-4-sulphonic acid and 1 g. of potassium bichromate are dissolved in 500 cc. of water. 80 cc. of 10% sulphuric acid, 300 cc. of 10% aqueous polyvinyl alcohol and 100 cc. of glycerine are added to this solution. This is cast on a paper support and dried.

A brown positive is obtained after processing as described in Example 1.

EXAMPLE 3 Negative material 30 g. of 1-methyl-sulphoamidonaphthol-Z, 30 g. of potassium metabisulphite, 40 g. of citric acid and 0.75 g. of benzotriazole are added to 1 litre of silver halide emulsion. This emulsion is coated on a support which is resistant to temperatures up to about 150 C., such as paper, and dried.

Positive material As in Example 1. A yellowish-brown image is obtained after processing as disclosed in Example 1.

EXAMPLE 4 Negative material 25 g. of 1-methylaminonaphthol-2, 30 g. of potassium metabisulphite, 30 g. of citric acid, and ml. of benzotriazole (5%) are added to one liter of silver halide emulsion. Other conventional additives can be used. The emulsion is coated on a paper support and dried.

Positive material 10 g. of 4-diazo-4'-rnethoxydiphenylamine-sulphonate,

Negative material 8 g. of p-aminophenol hydrochloride, 10 g. of potassium meta-bisulphite and 150 g. of sodium acetate are dissolved in water and added to 1 liter of silver halide emulsion. tabilizers and other conventional additives, for instance matting agents, can be used.

Positive material 10 g. of the diazoamino compound obtained from diazotized anthranilic acid and p-toluidine, 0.8 g. of sodium vanadate and 2.2 g. of sodium perborate are dissolved and added to 800 ml. of a 5% solution of polyvinyl pyrrolidone in water. 10 g. of citric acid and 10 0 ml. of glycerine are then added. The solution is cast on a paper support and dried.

After processing the 2 layers as disclosed in Example 1 a dark dyestuff positive is obtained.

EXAMPLE 6 Negative material 20 g. of 4-isopropylidene-aminophenol are dissolved in some dimethyl-formamide and added to 1 liter of silver halide emulsion. 10 g. of potassium metabisulphite, 150 g. of sodium acetate and 15 ml. of benzotriazole (5%) are then added. This emulsion is coated on a paper support and dried.

Positive material 10 g. of 4-diazo-4'-rnethoxydiphenylamine zinc chloride double salt, 0.7 g. of sodium molybdate, 2.5 g. of sodium bromate, 70 ml. of phosphoric acid (10%) and ml. of glycerine are added to 800 ml. of polyvinyl alcohol. The solution is cast on a paper support and dried.

After proceeding as described in Example 1 a deep colored laterally non-reversed positive of the printed original is obtained.

In the above examples the various formulations include hygroscopic ingredients (e.g. glycerine) that provide moisture which is recognized in the art as facilitating the transfer operation.

What we claim is:

1. In the process for the production of laterally nonreversed photographic positive images by hot pressing in unrnoistened condition a photographically exposed photosensitive silver halide emulsion layer against a transfer layer in which the emulsion layer contains a silver halide developer which before reaction with the silver halide couples with a diazo compound to form a dye, but after reaction with the silver halide does not form a dye, the transfer layer contains said diazo compound, both the emulsion layer and the transfer layer are supported on a base and have as their binding agents a colloid selected from the class consisting of gelatin, hydrophilic cellulose derivatives, polyvinyl alcohol, and polyvinyl pyrrolidone, and both layers are deposited from aqueous solution in such a manner that a small moisture content is retained for the transfer reaction, the improvement according to which there is added to the transfer layer prior to said hot pressing step a heavy metal salt of the class consisting of ammonium and alkali metal bichromates, molybdates, tungstates, vanadates, uranates, titanates, niobates and tantalates, copper sulfate, zinc sulfate, ferric nitrate, chromium alum, cerium nitrate, uranium nitrate and Reinecke salt to increase the speed of dye formation as well as the depth of color.

2. The combination of claim 1 wherein the concentration of the diazo compound in the transfer layer is about 0.5 to 2% by weight of the layer and the concentration of the salt is between about to by weight of the diazo compound.

3. The combination of claim 1 in which the transfer layer also contains an oxidizing agent of the class consisting of alkali and alkaline earth perborates, arsenates,

ersulfates, chlorates, bromates, iodates and nitrates.

4. The combination of claim 3 wherein the concentration of the diazo compound in the transfer layer is about 0.5 to 2% by weight of the layer, the concentration of the salt is about 5 to 10% by weight of the diazo com pound, and the concentration of the oxidizing agent is between 2 to 4 times the weight of the salt.

5. The combination of claim 1 wherein the developer is present in the silver halide emulsion layer in a proportion of between about 5 to 20 grams for each liter of silver halide emulsion.

6. The combination of claim 1 in which the developer is selected from the class consisting of aromatic amino, aromatic hydroxy and aromatic amino hydroxy compounds.

7. The combination of claim 1 in which the developer is para-amino phenol.

8. The combination of claim 1 in which the developer is an amino hydroxy naphthalene.

9. The combination of claim 1 in which the developer is an amino hydroxy compound in which the amino group is substituted by the radical --SO R, where R is selected from the class consisting of hydroxyl, lower alkyl and lower alltyl-phenyl groups.

10. The combination of claim 1 in which the silver halide emulsion is a solidified form of a liquid having a pH between about 4 and 7.

11. The combination of claim 1 in which the silver halide emulsion is a solidified form of a liquid having a pH between about 5.6 and 6.3.

12. The combination of claim 1 in which the transfer layer is a solidified form of a liquid having a pH between about 2 and 7.

13. The combination of claim 1 in which the silver halide emulsion is a solidified form of a liquid having a pH between about 4 and 7, the developer is present in the emulsion in a proportion of between about 5 to 20 grams per liter, the transfer layer is a solidified form of a liquid having a pH of between about 2 and 7, the concentration of the diazo compound in the transfer layer is between about 0.5 to 2% by weight of the transfer layer, and the concentration of the salt is about 5 to 10% by weight of the diazo compound.

14. A photographic transfer member having a support uniformly coated with a layer of a binding agent selected from the class consisting of gelatine, hydrophylic cellulose derivatives, polyvinyl alcohol, and polyvinyl pyrrolidone, said agent containing (1) a diazo compound that couples with a silver halide developer before the developer reacts with the silver halide to form a dye by such coupling, but after the developer reacts with the silver halide does not form a dye by such coupling, said developer being selected from the class consisting of aromatic amino, aromatic hydroxy and aromatic amino hydroxy compounds which undergo such coupling but which after developing a silver halide do not undergo such coupling; and (2) a salt of the class consisting of ammonium and alkali metal bichromates, molybdates, tungstates, vanadates, uranates, titanates, niobates and tantalates, copper sulfate, zinc sulfate, ferric nitrate, chromium alum, cerium nitrate, uranium nitrate and Reinecke salt, the layer being deposited from aqueous solution, the diazo compound being present in a concentration of about 0.5 to 2% by weight of the transfer layer, and the concentration of the salt being between about 5 to 10% by weight of the diazo compound, to increase the speed of said dye formation as well as the depth of color.

15. A photographic transfer member having a support uniformly coated with a layer of a binding agent selected from the class consisting of gelatine, hydrophylic cellulose derivatives, polyvinyl alcohol, and polyvinyl pyrrolidone, said agent containing (1) a diazo compound that couples with a silver halide developer before the developer reacts with the silver halide to form a dye by such coupling, but after the developer reacts with the silver halide does not form a dye by such coupling, said developer being selected from the class consisting of mo matic amino, aromatic hydroxy and aromatic amino hydroxy compounds which undergo such coupling but which after developing a silver halide do not undergo such coupling; (2) a salt of the class consisting of ammonium and alkali metal bichromates, molybdates, tungstates, vanadates, uranates, titanates, niobates and tantalates, copper sulfate, zinc sulfate, ferric nitrate, chromium alum, cerium nitrate, uranium nitrate and Reinecke salt, the layer being deposited from aqueous solution, the diazo compound being present in an concentration of about 0.5 to 2% by weight of the transfer layer, and the concentration of the salt being between about 5 to 10% byweight of the diazo compound; and (3) an oxidizing agent of the class consisting of alkali and alkaline earth perborates, arsenates, persulfates, chlorates, bromates, iodates and nitrates, and the concentration of the oxidizing agent is from 2 to 4 times the weight of the salt.

References Cited in the file of this patent UNITED STATES PATENTS 1,920,542 Zitscher et a1 Aug. 1, 1933 1,922,727 Ellis Aug. 15, 1933 1,964,358 Krieger June 26, 1934 2,066,918 Poser Jan. 5, 1937 2,113,944 Leuch Apr. 12, 1938 2,217,189 Sus Oct. 8, 1940 2,228,562 Dicterle Jan. 14, 1941 2,661,293 Land Dec. 1, 1953 2,747,999 Yutzy et al May 29, 1956 FOREIGN PATENTS 629,656 Great Britain Sept. 26, 1949 OTHER REFERENCES Foster et al.: An Introduction to General Chemistry, 3rd ed., Van Nostrand, 1947, pp. 104-05.

Richardson et 211.: General College Chemistry, 4th ed., Henry Holt, 1937, p. 153. 

1. IN THE PROCESS FOR THE PRODUCTION OF LITERALLY NONREVERSED PHOTOGRAPHIC POSITIVE IMAGES BY HOT PRESSING IN UNMOISTENED CONDITION A PHOTOGRAPHICALLY EXPOSED PHOTOSENSITIVE SILVER HALIDE EMULSION LAYER AGAINST A TRANSFER LAYER IN WHICH THE EMULSION LAYER CONTAINS A SILVER HALIDE DEVELOPER WHICH BEFORE REACTION WITH THE SILVER HALIDE COUPLES WITH A DIAZO COMPOUND TO FORM A DYE, BUT AFTER REACTION WITH THE SILVER HALIDE DOES NOT FORM A DYE, THE TRANSFER LAYER CONTAINS SAID DIAZO COMPOUND, BOTH THE EMULSION LAYER AND THE TRANSFER LAYER ARE SUPPORTED ON A BASE AND HAVE AS THEIR BINDING AGENTS A COLLOID SELECTED FROM THE CLASS CONSISTING OF GELATIN, HYDROPHILIC CELLULOSE DERIVATIVES, POLYVINYL ALCOHOL, AND POLYVINYL PYRROLIDONE, AND BOTH LAYERS ARE DEPOSITED FROM AQUEOUS SOLUTION IN SUCH A MANNER THAT A SMALL MOISTURE CONTENT IS RETAINED FOR THE TRANSFER REACTION, THE IMPROVEMENT ACCORDING TO WHICH THERE IS ADDED TO THE TRANSFER LAYER PRIOR TO SAID HOT PRESSING STEP A HEAVY METAL SALT OF THE CLASS CONSISTING OF AMMONIUM AND ALKALI METAL BICHROMATES, MOLYBDATES, TUNGSTATES, VANADATES, URANATES, TITANATES, NIOBATES AND TANTALATES, COPPER SULFATE, ZINC SULFATE, FERRIC NITRATE, CHROMIUM ALUM, CERIUM NITRATE, URANIUM NITRATE AND REINECKE SALT TO INCREASE THE SPEED OF DYE FORMATION AS WELL AS THE DEPTH OF COLOR. 